Posted
by
Soulskillon Tuesday May 15, 2012 @05:49PM
from the volunteers-for-further-tests-may-raise-their-hands dept.

JSBiff sends this quote from MITnews:
"A new study from MIT scientists suggests that the guidelines governments use to determine when to evacuate people following a nuclear accident may be too conservative. The study (abstract), led by Bevin Engelward and Jacquelyn Yanch and published in the journal Environmental Health Perspectives, found that when mice were exposed to radiation doses about 400 times greater than background levels for five weeks, no DNA damage could be detected. Current U.S. regulations require that residents of any area that reaches radiation levels eight times higher than background should be evacuated. However, the financial and emotional cost of such relocation may not be worthwhile, the researchers say."

Funny, but "no detectable DNA damage" is not the same as "no DNA damage or other side effects". This study would need to be much longer term and need to look for more than obvious DNA damage for me to trust it, personally. It was only 5 weeks!

This study would need to be much longer term and need to look for more than obvious DNA damage for me to trust it,

This study will never be trustworthy.

The danger to civilians from a nuclear accident is unlikely to come from background dose. That's more likely to be the exposure mode for workers and people very close to the incident.

found that when mice were exposed to radiation doses about 400 times greater than background levels for five weeks, no DNA damage could be detected.

No surprises there, but they didn't test what would happen when the mice ingested radioactive particulates, or when their entire food chain or water table was contaminated. Those are the real dangers from nuclear accidents.

Are you talking about chemical poisoning, or magical evil pixie dust. 125I decays emitting low-energy gamma radiation (the type that gets adsorbed adversely by living things). Eating this will have no different an affect than living right under it, as an object like a person, or mouse, is not a relevant shield for gamma radiation.

Now, if we were talking about inhaling dusted alpha emitters, then you'd have a point. However, those are either heavy metals, oxidize and drop out of the air, or decay rapidly to long-term emitters. The dust will be much more poisonous than dangerous as a radioisotope.

A recently published study in the Journal of Environmental Radioactivity confirms that the radioactive fallout from the Fukushima nuclear disaster reached Europe (Lithuania), and included plutonium. Likewise strontium (89 and 90) levels were elevated globally.

The amounts were tiny, but randomly sized/distributed particulates are notoriously hard to measure and map.

This is literally examining the molecules on the wall to find out why the room stinks when there's an elephant in the middle of the room shitting all over the floor. You may find some residual fecal matter from someone not washing their hands properly after leaving the bathroom. But that won't be the main reason for the stink. In fact, it won't be stinking because there won't be enough of them to register in anyone's noses.

125I decays emitting low-energy gamma radiation (the type that gets adsorbed adversely by living things). Eating this will have no different an affect than living right under it...

Not totally correct. 125I will be selectively absorbed by the thyroid gland which will experience a much higher effective dose than any other part of the body. Similarly, the isotopes of strontium (90Sr is the main culprit) are similar enough to calcium that the bones absorb them preferentially and receive a higher dose from it.

Right, what special magical property of the environment is this that relegates 'particles contributing to background radiation' external to humans? You do know that the primary culprit in 'background radiation' is radon GAS (e.g. an inhalant)...

And ultimately you are making an assumption not in evidence (e.g. that 'natural sources' of radiation are primarily absorbed externally while radiation doses from some 'accident' are primarily ingested or inhaled...not necessarily true in either case).

Oh please, you're not +3 insightful, you're an idiot. "background dose" is a unit, and refers to the average background radiation exposure of 360 mrem per year. It is not a dose that you are exposed to unaware in a nuclear accident. When mice are given are given 400 times the background dose it means they are given 400 mrem per day.

you're an idiot. "background dose" is a unit, and refers to the average background radiation exposure of 360 mrem per year.

I keep forgetting that you have to explicitly explain everything on Slashdot or you'll be challenged on every minuscule aspect of your comment. Nevertheless, please read the Wikipedia article on background radiation, specifically the Human-caused background radiation section. http://en.wikipedia.org/wiki/Background_radiation [wikipedia.org].

But I'll repeat: Measuring the effect of steady-state external radiation, as this study has done, gives almost no insight at all on the effect of ingesting alpha-emitting particula

Really? Geez, let's be self evident...you never base 'public policy' off of 1 study...the researchers clearly indicate a need for further study...but the data point is valuable, especially when juxtaposed against the FUD generated by people such as yourself...in fact the study gives 0 evidence of the effect of 'ingested alpha-emitting particles' since that's not what was tested...but that's like saying basing policy for cyanide ingestion on an arsenic study is 'wrong'..DUH! of course it would be...

Funny, but "no detectable DNA damage" is not the same as "no DNA damage or other side effects". This study would need to be much longer term and need to look for more than obvious DNA damage for me to trust it, personally. It was only 5 weeks!

Not that much longer, a mouse goes from infancy to maturity in about 6 to 10 weeks, a year can get you a generation or two. A mouse can have 5 - 10 litters in a year and their lifespan is 9 to 12 months; 5 weeks for a mouse is like 20 years for a human.

Did you read the study linked to? it references mean doses of 16.8 & 83.6 cGy delivered as 'one dose' at various stages of prenatal and postnatal development of the entire population, particularly at times when the beagles would be more susceptible than the 'general population'...stated this as 'not good' is way overstating any conclusions...in fact the study in this posted article is specifically looking at the opposite effect 'low dose over a long time period' (equivalent of 105 cGy/year not anywhere

Sophisticated molecular and genetic analyses were not available in 1950s - 70s when many experiments investigating the effects of radiation on plants and animals took place; most were crude LD50 and cancer frequency tests conducted at moderate to very high doses, few were conducted at low doses (0.1 Gy) where cells could potentially repair the damage caused. This has all changed in the last ~20 years.

Sophisticated laboratory techniques now detect and observe the defence & repair mechanisms that operate in cells and whole organisms at low doses (100 mSv, ~0.8% increased risk of cancer in humans). For example, healthy people's cells repair all radiation induced DNA Double Strand Breaks (DSBs) within 24-hours after a CAT scan, indicating little or no additional risk of cancer. It is clear from resent experiments that living organisms are not passive accumulators of radiation damage but they actively combat and repair the damage done. After all, life involved with radiation and 3.5-3.8 billion years ago radiation levels were many times greater then now, it was necessary to evolve sophisticated error correction mechanisms. Indeed, it is likely that radiation is far less harmful or harmless below a certain threshold, possibly ~ 20 mSv year.

Do you live near a freeway? That doubles the rate of atherosclerosis. Air pollution kills hundreds of thousands a year in the US, and also causes other significant morbidity like asthma in children. Way more dangerous that a measly radiation dose. Yet, I don't see people wanting to evacuate from around coal plants and freeways.

The article says low levels of exposure for five weeks resulted in no DNA damage. Five weeks is nothing, people living in contaminated areas will be there for years, and once radioactive material gets inside them it will be there for the rest of their lives. That is where the biggest danger is, long term internal exposure to material absorbed by the body into the organs.

The interesting thing to note (if this study is correct) is that they observed a difference between an acute dose and a chronic one. Our radiation health data is mostly based on acute doses - the Hiroshima and Nagasaki bombings, mainly. The low dose risk estimates are basically based on that, extrapolated downwards linearly.

If acute dosing behaves differently to chronic, that model wouldn't be appropriate.

The interesting thing to note (if this study is correct) is that they observed a difference between an acute dose and a chronic one. Our radiation health data is mostly based on acute doses - the Hiroshima and Nagasaki bombings, mainly. The low dose risk estimates are basically based on that, extrapolated downwards linearly.

If acute dosing behaves differently to chronic, that model wouldn't be appropriate.

Hiroshima and Nagasaki radiation victims are some of the few human models that have been studied, but the DOE (and probably other government agencies around the world) did extensive testing on the effects of radiation at various doses using animal models. In one large-scale study I know of they used two exposure groups of beagles, one using the radioactive isotopes the bomb victims were exposed to in order to establish a baseline model correlation (human effects vs. effects observed in laboratory animals) and the other group exposed to isotopes expected to result from nuclear accidents and the new generation hydrogen bombs (different fallout characteristics than the original atomic bombs). Quite a bit of research was done on this, especially during the 1960s and 1970s. They also experimented with direct gamma exposure at various levels; rumor has it (I've never seen published results on the experiments) that there was a sweet spot in the gamma ray exposure scenario that actually lead to significantly longer lifespan than the control group, with many theories as to the cause.

Interesting. But while there were very many experiments carried out in the 1960-70s, the radiation doses applied were generally much higher then the background levels we are interested in now. People are worried over a few extra MiliSieverts a year.

Scientists in the 1960-70s were were not able to observe subtle cellular effects, typical defence and repair mechanisms, that operate at and just above background levels of radiation (20 mSv). They were mostly crude LD50 and cancer frequency tests. Very few experiments investigated doses 0.1 Gy (about 100 mSv & 0.8% increase in human cancer risk). And the few experiments that did involve low doses gave confused results because of poor statistical certainty (some even suggested Radiation Hormesis, as you alluded to).

That's why these resent experiments are so important and interesting, they're finally investigating how organisms cope with low level radiation, and indeed they suggest the risks are grossly overestimated.

The problem with these studies is that they don't test the particular conditions people are worried about: long term low level exposure due to radiation inside the body and organs. Nuclear plant workers are the best benchmark we have for that, and sure enough rates of cancer are pretty consistently shown to be higher among that group.

The problem with these studies is that they don't test the particular conditions people are worried about: long term low level exposure due to radiation inside the body and organs. Nuclear plant workers are the best benchmark we have for that, and sure enough rates of cancer are pretty consistently shown to be higher among that group.

That's not right.

1. The risks of internal radiation are reasonably well understood from observations of patients given injections of ‘Thorotrast’, Radium dial painters exposed to 226 Ra and 228 Ra & patients given 224 Ra for medical conditions, occupational exposure of uranium miners to radon, and residential radon exposure etc.

IIRC, for that one the exposed group had a different age profile to the unexposed group. As cancer risk increases with age, that explained the difference. Which just goes to show that the idea of a controlled experiment isn't just scientific pedantry - I doubt we'll ever get a satisfactory answer from that kind of study.

That's not the best evidence. The most appropriate literature for this exposure is that pertaining to nuclear industry workers.
This is how the guidelines of 20mSv per year were derived. See this study for instance: http://www.ncbi.nlm.nih.gov/pubmed/17388693 [nih.gov]
there's no need to reinvent the wheel here, there is ample evidence that nuclear workers have higher risks of cancer and a population exposed to fallout from a reactor could reasonably be expected to have similar or worse outcomes (due to increased

That's a very difficult kind of test to do though, because making sure that radiation dose is the *only* difference between groups is virtually impossible. Even the abstract of that paper says that "Further studies will be important to better assess the role of tobacco and other occupational exposures in our risk estimates.". At least this mouse study allows for a proper controlled trial, and the Hiroshima data, while not perfect, is much less prone to such factors than your linked one.

Also, reading the part that says "Among 31 specific types of malignancies studied, a significant association was found for lung cancer (ERR/Sv 1.86, 90% CI 0.49, 3.63; 1457 deaths)" rather reminded me of this [xkcd.com].

To me the much more interesting studies are those being done in the Chernobyl Exclusion Zone, while they are obviously not controlled or double blind they do provide better feedback about actual contamination results than the lab experiment with a fixed gamma source.

The low dose risk estimates are basically based on that,
extrapolated downwards linearly.

This is false. What you are describing is the
linear no-threshold model [wikipedia.org] which was proposed by rabid anti-nuke
fanatics years ago and rejected by the industry and by regulators
alike. The threshold below which radiation levels were considered
to be safe has decreased by orders of magnitude as more information
was gleaned about health effects of low level radiation.
The assumption by the industry has almost always been that
adverse health effects magically vanish unless there is scientific
proof that they

They weren't talking about poisonous materials like iodine and strontium isotopes being released into the atmosphere. They were talking about Radiation. It says that very specifically. If radiation levels 8x greater than normal are present... evacuate. They think that should be set to 100x. Which makes sense. Would changing that regulation mean that if radiation levels were only at 10x background levels, and the sky was raining Cesium that they wouldn't evacuate? Of course not.

Where do you think radiation comes from? If there are high levels of radiation it's because there is radioactive material near by. In most accidents that material will be small enough to get inside you. That's why after you evacuate you need to wash thoroughly.

Get inside you? Specifically, the materials you need to worry about are materials your body uses that in their isotope form have a relatively long half life.Just as a rough example, if the material released from the reactor was Iodine-124, it's bad because your body does use Iodine, but it has a halflife of just a couple of days. It's not really that dangerous, and an evacuation of surrounding area would likely not be warranted if the levels are relatively moderate. If Iodine-129 is getting released, it has

I was under the impression that half life if related to how many emissions or the strength of the emission the particle will give off and it is those radiation emissions which are dangerous. It's the reason why plutonium, with a half life of 80 million years, is dangerous to the human body as a toxic agent rather than a radioactive agent. I'd suspect that I-129 with a half life of 15 million years is either mostly harmless since the body does use iodine but if it is harmful that is most likely to come from

Yes, it is long term. At least it's long compared to the normal procedure for these types of experiments. What they were trying to determine is if the effects exposure are dependent on the rate as well as the total dose. From the linked abstract:

"these results demonstrate in an in vivo animal model that lowering the dose-rate suppresses the potentially deleterious impact of radiation"

This study doesn't necessarily imply that exposure to 400 times background radiation levels are safe indefinitely.

You missed the part about 400 times higher than background levels, I take it? 400x background over five weeks, and they still can't detect DNA changes "using the most sensitive techniques available".

If the current guidelines say 8x background levels is the max before "holy shit everyone is going to die get the fuck out now" levels of evacuation, it might just be because it's a guess erring on the side of caution. Another way to look at it: that kind of evacuation and the ensuing panic might very well kill m

The article says low levels of exposure for five weeks resulted in no DNA damage. Five weeks is nothing, people living in contaminated areas will be there for years, and once radioactive material gets inside them it will be there for the rest of their lives.

once radioactive material gets inside them it will be there for the rest of their lives.

Wrong. Many radioactive isotopes aren't absorbed by the body and are flushed out rapidly, and some of the most damaging particles (alpha emitters in particular) are at their worst when airborne, only staying 'in' your body for the length of a breath.
There are some isotopes that are absorbed easily (namely Iodine), but they are the minority. There is not a single "Radiation", there are a staggering number of different radioactive elements, and for each one, the chemistry matters far more than the half-life.

One has to take care in this case to distinguish between the bio-retention of chemically pure compounds, and what happens in the real world, which is radioactive compounds embedded in small clumps with other material that makes them stick around, e.g. in the lungs. Especially if they get pulled through a cigarette or car engine on their way there.

Did you miss the part where they tested at 400x but the standard says 8x is too much? Over five weeks, that's roughly equal to the exposure they'd see in 4.8 years of 8x background. Assuming the food/water the mice were eating was equally contaminated, it's a pretty fair test.

Maybe you, and the mods, might want to familiarize yourself with lab mice. They are precisely breed.We know pretty much everything about them. For example, you can get mice that will get a specific cancer at 2 months, and it happens every time. 'only' 99.9% guarantee, but I have never seen one in a control not get cancer at the expected time

SO, for this test, 5 weeks is fine. But with ALL STUDIES, one isn't enough. DO several, control different variables, move to different species.

It isn't enough because with low doses of radiation the probability of DNA being damaged in a way that leads to cancer over a five week period is very low. They want to extrapolate from that period up to decades in humans, but the error is too great and the results don't match those we have observed in people receiving even lower levels of exposure.

Spoken like someone who knows nothing about radioactive materials and how they interact biologically.

Few radioactive elements stay in the body permanently. Most of them like Cs137 and I131 cycle through the body in days to couple of months. Plutonium is one of the few that has a biological half life of significant length, and it is one of the lesser radioactive isotopes. The most likely isotope you'd encounter after a nuclear accident that has a long biological half-life is Strontium-90.

The effective half-life of an isotope is measured by taking into account the physical half-life of the isotope and the biological half-life of an isotope. Thus, an element like Strontium 90 has an effective half-life of about 18 years while plutonium has an effective half-life of about 50 years (due to their propensity for gather in bone). Cesium has an effective half-life of about 70 days, and iodine has an effective half-life of about 7.6 days.

With that in mind, chronic long term exposure can only occur if they are taking in enough radioactive materials to replace those that are expelled from the body. To accumulate, you'd need to be taking in more.

Given the number of times one experts study is tossed out by another experts study why should I trust this 1 study, and what kind of assurances does anyone have that their isn't some kind of error and will be tossed out or ignored with the next study. How am I to know if this study wan't done to justify low level back scatter scanners at air port, and has fallen victim to confirmation bias of one form or anther?

I agree. Last I checked I wasn't a mouse. I don't really care if one of the greatest survivors on Earth handle radiation. Might as well tell me how high the background radiation can get for cockroaches before you can detect damage. That wouldn't be a good danger level for a human. As someone whose worked with people who sued to do some very expensive studies for drugs, human trials very frequently turn out different than animal trials, even on things where the best prior research shows a strong correlation

More importantly: Why should we trust the government? Japan's government said the Fukushimi area was "safe" and now we're discovering the soil is polluted with radiation.

We should buildin a large margin-for-error, in order to account for politicians' tendency to lie. "It's only 400 times above normal. We don't need to evacuate - it's safe according to scientists." Meanwhile actual levels are 40,000 times which is deadly.

The relevance of this study is not being questioned because of a concern of reproducibility but of the idea that a minor study where five weeks of exposure to a specific quantity of radiation was not found to have caused detectable disruption to genetic heredity would become equatable to saying that any low level radiation exposure is not worth being concerned enough about to inform or evacuate an area over. Their data is a single point on the scale of duration and quantity of exposure, and for each reprodu

Given the number of times one experts study is tossed out by another experts study why should I trust this 1 study, and what kind of assurances does anyone have that their isn't some kind of error and will be tossed out or ignored with the next study. How am I to know if this study wan't done to justify low level back scatter scanners at air port, and has fallen victim to confirmation bias of one form or anther?

So, why should you believe that 8x normal level is a reasonable limit? It's not like there's any

This is why I don't pay attention to ANY popularized publication of scientific results.

BPA - causes all sort of problems.

Eating GMO corn - rat livers have problems

Vaccine - causes autism

Yadda yadda, every day in the news. Then you dig into the toxicological assessments of the collected studies and you find - BPA, not one of the studies was reproducable. GMO corn study had bogus statistics used to manipulate results. The vaccine study was out and out fraud.

How can they really test every cell to determine if there has been damage? A longer term study monitoring cancer rates would be more useful.
I'm not saying that we shouldn't question the current guidelines, but changing them because of a short study like this would be crazy.

If you follow the links to the abstract, it actually explains what they measured. Apparently, certain types of DNA damage leave easily measured chemical signatures. They also dosed them with the same radiation total over a short period of time and observed damage.

This is akin to turning your thermostat up 10 degrees for a few weeks as opposed to heating your house up to 500 degrees for a minute.

I'm not saying I want to invest in cheap Fukushima real estate. I'm just saying that maybe this science isn't as junky as some Slashdotters think.

They also dosed them with the same radiation total over a short period of time and observed damage.

This is akin to turning your thermostat up 10 degrees for a few weeks as opposed to heating your house up to 500 degrees for a minute.

I'm not saying I want to invest in cheap Fukushima real estate. I'm just saying that maybe this science isn't as junky as some Slashdotters think.

If I put an egg in warm water for a few hours, I'll have the same egg -- one that I can use to make an omelette. If I put it in boiling water for 10 minutes, I'll have hardened. Similar amounts of energy, different results.

A 400x radiation dose over 5 weeks does not necessarily a long term 8x dose make, and Slashdotters are absolutely correct to call this out.

A 400x radiation dose over 5 weeks does not necessarily a long term 8x dose make, and Slashdotters are absolutely correct to call this out.

That sort of comparison is exactly what this study is calling out, too. You know how that "8x background = evacuation" threshold was developed? By measuring the effects of a short-term dose just low enough to avoid acute radiation poisoning, and assuming it's equivalent to a low-level long-term dose that provides as much total radiation. (It's called the "linear no-thr

They can't. That's why they formulate the experiment with an appropriately-chosen hypothesis and a control.

The question is whether the linear-to-zero dose model is accurate. It's the most conservative reasonable model and it has some experimental basis, but low-rate radiation isn't well-tested. In this model, at the low end of dosing, only the total dose, not the rate at which it's delivered, matters. (That is, you're in the "causes cancer" realm of radiation and not "radiation poisoning".)

Just pointing out that in most places background is pretty low. Eight times higher in a low background area isn't the same as say eight times higher in an area that already has a higher than normal background count (for example New Hampshire, the Granite (and slightly more radioactive than normal) State.

Also internal exposure increases the damage from radiation by a factor of ten. At a does the equivalent of 80x background, you might want to move.

Seems a bunch of people really don't understand the scale of how low "background level" really is, how quickly levels can drop as the worst isotopes rapidly decay, or how the body repairs over time. That last one is maybe okay; we really haven't put a lot of study into anything beyond immediate exposures, so no one has a good understanding of that; or, I should say, HAD. And to see so many first reactions to this new science being "I refuse to believe it!"? Very disappointing. It's amazing how much disbelief a purportedly "scientific" group can conjure when scary radiation is mentioned.

Btw, 100x background for 5 weeks is still less than the maximum year-long dose. Check the should-now-be-iconic xkcd radiation chart [xkcd.com].

My teacher, who has a PhD in Radiobiology, once did an experiment on the subject.
He had two groups of mice. One of the groups was exposed to laser radiation. The other one was a control group. Both groups were then subjected to high energy ionizing radiation. Guess what: the ones who were exposed to the laser had a high survival rate than the ones who were not.
So there is this belief that very low levels of radiation might actually activate your body's repair system without doing much damage. The caveat m

Radiation induce cancer, but that does not mean cancer will thrive. It needs to be promoted. Diet and environment contain promoters. I suspect the mice in the experiment were not fed with growth hormone treated beef, for instance. First-world humans tend to have a diet that highly promotes cancer, therefore their risk may be higher than the mice in the study.

There's nothing I detest more than some douche who has spent some timeat a university telling us all "we have nothing to fear".

Oddly, there's nothing I detest more than some idiot who is terribly afraid of something long after it's been proven to be safe.

I'd happily live in an area with 200x the level of background radiation (hey, my AT&T reception couldn't get any worse). The best benefit is that I can be sure compete morons like yourself will not be neighbors.

They said that about DDT.

Um, yeah...because DDT is safe [freerepublic.com]. And millions have been killed from malaria that could have been saved without idiots like yourself "protecting" them.

Supporting those black natives, however, are two researchers, Richard Tren and Roger Bate, whose Malaria and the DDT Story, recently published by the Institute for Economic Affairs in London, shows how to foster both a healthier and an environmentally friendlier Third World. Greenpeace, in its self-assurance, embodies a contemporary cultural imperialism as offensive as any Jesuit's.

We need to bring back DDT for killing bed bugs! It's about the single best way to kill the things and there would be little concern of bioaccumulation in that application. Oh, and calling someone a moron and then linking to the freepers is about the funniest thing I've ever read on the internet and I've been here since 1993 =)

And DDT is extraordinarily safe for humans. Prof Kenneth Mellanby lectured on it for more than 40 years, and during each lecture he would eat a pinch.

I'm sure you could find someone who has been smoking 20 cigarettes a day for 40 years and who still is relatively healthy.Are cigarettes "extraordinarily safe for humans" ?Is falling from a 20 m roof "extraordinarily safe for humans" because some guy survived it?

I have no clue about DDT, I'm just saying that this logic is deeply flawed.

>>I have no clue about DDT, I'm just saying that this logic is deeply flawed.

It's akin to a scientist saying that it is safe to drink non-radioactive water from a nuclear power plant's cooling power, and putting his money where his mouth is by drinking it.

It's entirely safe for humans in the dosage levels used to control bed bugs and malaria, which require much lower dosages than the wholesale blanketing of farmlands we were doing before. While it is toxic (http://en.wikipedia.org/wiki/DDT#Effects_on_

At Chernobyl - wildlife have been reported to have lower survival and reproduction rates, with clear pathological effects to sperm.This data point may be valid (it's a complex problem),

Not a bad point, and Chernobyl should figure in most radiation data comparisons due to its nature. However, radiation levels vary wildly in the area: the animals could have eaten their food from a hotspot even if the background would have been tolerable (which we don't really know either.)

but you have to wonder when the sponsor (DOE) reason to want this outcome.

No we don't. But, I'll say this much: the DOE is involved with coal power. The DOE is involved with nuclear power. Clearly, they're simultaneously plotting to replace coal with nuclear and nuclear with coal.